Object lens drive device, and disc recording and/or reproducing apparatus

ABSTRACT

The present invention is directed to an object lens drive device adapted for moving an object lens in a focus direction of optical axis direction and in a tracking direction perpendicular to the optical axis direction, and includes a fixed position provided in such a manner that a supporting shaft is projected, a movable portion comprised of an object lens, and a bobbin adapted so that the object lens is attached and a hole through the supporting shaft is inserted is formed, the bobbin being supported movably along the supporting shaft and rotatably with the supporting shaft being as center, a drive portion including a magnet portion provided at either one of the fixed potion and the movable portion, and a coil portion provided at the other portion to move the movable portion along the supporting shaft to thereby move the object lens in the focus direction, and to rotate the bobbin with the supporting shaft being as center to thereby move the object lens in the tracking direction, and supporting means including a magnetic member for supporting the movable portion in the state inclined with respect to the supporting shaft.

This application is a con of Ser. No. 10/433,613 Jun. 18, 2003 U.S. Pat.No. 7,046,590.

TECHNICAL FIELD

The present invention relates to an object lense drive device adapted sothat a movable portion in which object lens (objective) is attached issupported movably along the supporting shaft and rotatably with thesupporting shaft being as center, and a disc recording and/orreproducing apparatus using such an object lens drive device.

BACKGROUND ART

As an apparatus adapted for carrying out recording of informationsignals ono a disc-shaped recording medium such as optical disc, etc.and for carrying out reproduction (playback) of information signalsrecorded on the disc-shaped recording medium, there are used disc driveapparatuses. In the disc drive apparatuses of this kind, there is usedan object lens drive device adapted for converging light beams emittedfrom light source onto the signal recording surface of a disc-shapedrecording medium to irradiate them thereto, and for allowing such lightbeams to follow recording tracks formed at the disc-shaped recordingmedium. The object lens drive device is adapted so that a movableportion in which an object lense (objective) for converging light beamsemitted from light source onto the signal recording surface of thedisc-shaped recording medium is attached is supported movably along thesupporting shaft and rotatably with the supporting shaft being ascenter. The object lens drive device carries out a focus control to movethe movable portion in the axial direction of the supporting shaft inparallel to the optical axis of the object lens in accordance with focuserror signal to thereby carry out control of in-focus position of theobject lens, and carries out a tracking control to rotate the movableportion in the direction about the axis of the supporting shaft in adirection perpendicular to the optical axis of the object lens inaccordance with a tracking error signal so that light beams followrecording tracks of the disc-shaped recording medium.

In the case of the object lens drive device of the shaft slidable androtatable type adapted so that the movable portion in which object lensis attached is supported at the supporting shaft, as compared to theobject lens drive device in which the movable portion iscantilever-supported by elastic displacable supporting arm with respectto the fixed portion so that it is permitted to undergo displacement inthe focusing direction and in the tracking direction, since weightbalance of the movable portion is satisfactory, there are the meritsthat vibration proof characteristic in the tracking direction of thedirection perpendicular to the focusing direction of the direction inparallel to the object lens is excellent, and displacement of themovable portion by self-weight is small, etc.

In the object lens drive device of the shaft slidable and rotatabletype, since supporting shaft is inserted into a supporting hole formedat bobbin constituting the movable portion so that the movable portionis supported rotatably in a direction about the axis of the supportingshaft and slidably in the axial direction, there is a predeterminedclearance between the supporting hole and the supporting shaft. As aresult, at the time of focus control when the movable portion is movedin a direction in parallel to the optical axis of the object lens, andat the time of tracking control when the movable portion is rotated in adirection perpendicular to the optical axis direction of the objectlens, the movable portion would be inclined in an arbitrary directionwith respect to the supporting shaft by clearance between the supportinghole and the supporting shaft. When the movable portion is inclined inan arbitrary direction with respect to the supporting shaft in this way,the inclination direction is changed when the movable portion is movedin the focusing direction or in the tracking direction so that theoperation becomes unstable. As a result, it becomes impossible toprecisely carry out the focus control and the tracking control of theobject lens. It becomes impossible to allow light beams to be preciselyin focus with respect to the signal recording surface of the disc-shapedrecording medium and to allow them to precisely follow recording tracks.It becomes impossible to precisely carry out recording or reproductionof information signals.

In view of the above, in the object lens drive device of the shaftslidable and rotatable type provided in the conventional disc driveapparatus, e.g., tension in a predetermined direction is rendered to themovable portion by making use of elasticity of flexible printed board toalways incline the movable portion in a predetermined direction withrespect to the supporting shaft to thereby prevent change (fluctuation)in the inclination direction of the movable portion.

As stated above, in the object lens drive device adapted for renderingtension in a predetermined direction to the movable portion by theflexible printed board to prevent change (fluctuation) in theinclination direction of the movable portion, when the movable portionis caused to undergo movement operation, tension changes. As a result,it is impossible to securely prevent change (fluctuation) in theinclination direction of the movable portion. Thus, it becomesimpossible to precisely carry out focus control and tracking control ofthe object lens.

In the disc drive apparatus which can be used as portable equipment,attitude of the object lens drive device changes in dependency upon usecircumstances. Thus, direction of gravity with respect to movementdirection of the movable portion changes. By influence of this gravity,inclination direction with respect to the supporting shaft of themovable portion changes. As a result, the operation of the movableportion becomes unstable.

In the object lens drive device of the shaft slidable and rotatabletype, in order to reduce, as minimum as possible, inclination angle wheninclination with respect to the supporting shaft of the movable portionis changed, there exist some object lens drive devices in which lengthof the supporting hole of the movable portion through which thesupporting shaft is inserted is elongated. However, when length of thesupporting hole is elongated, it becomes difficult to realize thinstructure of the object lens drive device.

In order to prevent inclination with respect to the supporting shaft ofthe movable portion, there is also proposed an object lens drive deviceadapted for rendering biasing force in a direction perpendicular to thefocusing direction to the movable portion to press the movable portiononto the supporting shaft to allow it to slide and rotate in the statecaused to be linearly in contact therewith. In such an object lens drivedevice, not only slidability with respect to the supporting shaft of themovable portion is deteriorated because the movable portion is caused tobe linearly in contact with the supporting shaft, but also the centeraxis of the supporting shaft and the center axis of the supporting holeare not caused to be in correspondence with each other. For this reason,the movable portion is not permitted to be smoothly slid and rotatedwith respect to the supporting shaft, and it also becomes impossible tocarry out precise focus control and tracking control in accordance withfocus error signal or tracking error signal.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a novel object lensdrive device which can solve problems that conventional object lensdrive devices as described above have, and a disc recording and/orreproducing apparatus using such an object lens drive device.

Another object of the present invention is to provide an object lensdrive device which can realize precise focus control corresponding tofocus error signal, and can realize precise tracking controlcorresponding to tracking error signal, and a disc recording and/orreproducing apparatus using such an object lens drive device.

A further object of the present invention is to provide an object lensdrive device which can realize miniaturization of the device itself, anda disc recording and/or reproducing apparatus using such an object lensdrive device.

An object lens drive device proposed in order to attain objects asdescribed above comprises: a fixed portion provided in such a mannerthat a supporting shaft is projected; a movable portion composed of anobject lens, and a bobbin adapted so that the object lens is attachedand a hole through which the supporting shaft is inserted is formed, thebobbin being supported movably along the supporting shaft and rotatablywith the supporting shaft being as center; a drive portion including amagnet portion provided at either one of the fixed portion and themovable portion, and a coil portion provided at the other portion tomove the movable portion along the supporting shaft to thereby move theobject lens in a focus direction, and to rotate the bobbin with thesupporting shaft being as center to thereby move the object lens in atracking direction; and supporting means for supporting the movableportion in the state inclined with respect to the supporting shaft.

The supporting means comprises a magnetic member attached to the movableportion to hold the movable portion at the neutral position in the focusdirection and in the tracking direction in cooperation with the driveportion. The magnetic member is attached to the movable portion in amanner inclined with respect to the supporting shaft.

As the supporting means constituting the object lens drive deviceaccording to the present invention, there may be used supporting meanscomprising a magnetic member attached to a movable portion to hold themovable portion at the neutral position in the focus direction and inthe tracking direction in cooperation with the drive portion, and aflexible printed wiring board adapted so that a portion thereof isrespectively attached to the fixed portion and the movable portion tosupply power to the coil portion.

The flexible printed wiring board used here is attached in such a mannerthat width direction of a junction portion which connects the fixedportion and the movable portion is different from the focus direction,and is different from the tracking direction.

In the object lens drive device according to the present invention, inthe state where power is not supplied to the coil portion, position inthe focus direction with respect to the fixed portion of the movableportion by balance between gravity and elastic force of the flexibleprinted wiring board is set at the fixed portion side with respect tomovement end of the fixed portion side within the movement range in thefocus direction of the movable portion.

A disc recording and/or reproducing apparatus according to the presentinvention comprises: a rotational drive unit adapted so that a disc isloaded to rotationally drive the loaded disc; an optical pick-up; and afeed mechanism for moving the optical pick-up in a radial direction ofthe disc. The optical pick-up used here comprises an object lens driveunit including a fixed portion provided in such a manner that asupporting shaft is projected, a movable portion composed of an objectlens and a bobbin adapted so that the object lens is attached and a holethrough which the supporting shaft is inserted is formed, the bobbinbeing supported movably along the supporting shaft and rotatably withthe supporting shaft being as center, a drive portion including a magnetportion provided at either one of the fixed portion and the movableportion, and a coil portion provided at the other portion to move themovable portion along the supporting shaft to thereby move the objectlens in the focus direction, and to rotate the bobbin with thesupporting shaft being as center to thereby move the object lens in thetracking direction, and supporting means for supporting the movableportion in the state inclined with respect to the supporting shaft.

Still further objects of the present invention and practical meritsobtained by the present invention will become more apparent from thedescription of the embodiments which will be given below with referenceto the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a disc drive apparatus in which anobject lens drive device according to the present invention is used.

FIG. 2 is a perspective view showing the object lens drive device in thestate where cover is separated.

FIG. 3 is an exploded perspective view of the object lens drive device.

FIG. 4 is a plan view of the object lens drive device shown in the statewhere cover is detached.

FIG. 5 is a cross sectional view along the V-V line of FIG. 4 shown inthe state where cover is attached.

FIG. 6 is a side view of movable portion indicating the relationshipbetween magnetic member and supporting hole.

FIG. 7 is a side view showing the state where the movable portion isoperated.

FIG. 8 is a plan view showing magnetic member used in the object lensdrive device according to the present invention.

FIG. 9 is a graphic diagram showing the result in which the relationshipbetween inclination angle with respect to supporting hole of magneticmember and produced angular moment (rotation torque) is measured.

FIGS. 10 to 12 show the result in which the relationship betweenposition in focusing direction of movable portion and inclination anglewith respect to supporting shaft portion of movable portion is measuredwith respect to respective installation states of the movable portion,wherein FIG. 10 is a graph showing measurement result in the state whereaxial direction of supporting shaft portion is vertical direction, FIG.11 is a graph showing measurement result in the state where axialdirection of supporting shaft is horizontal direction and object lens isplaced at the lower portion of supporting shaft, and FIG. 12 is a graphshowing measurement result in the state where axial direction ofsupporting shaft is horizontal direction and object lens is placed atthe side direction of the supporting shaft.

FIGS. 13 to 15 show the result in which the relationship betweenposition in focusing direction of movable portion and inclination anglewith respect to supporting shaft of movable portion is measured withrespect to respective installation states of movable portion inconventional object lens drive device, wherein FIG. 13 is a graphshowing measurement result in the state where axial direction ofsupporting shaft is vertical direction, FIG. 14 is a graph showingmeasurement result in the state where axial direction of supportingshaft is horizontal direction and object lens is placed at the lowerportion of supporting shaft, and FIG. 15 is a graph showing measurementresult in the state where axial direction of supporting shaft ishorizontal direction and object lens is placed at the side direction ofsupporting shaft.

FIG. 16 is a perspective view showing another example of the object lensdrive device according to the present invention.

FIG. 17 is an exploded perspective view showing an object lens drivedevice of another example.

FIG. 18 is a plan view showing the object lens drive device of anotherexample in the state where cover is detached.

FIG. 19 is a cross sectional view along IXX-IXX line of FIG. 18 shown inthe state where cover is attached.

FIG. 20 is a rear surface view of the object lens drive device ofanother example.

FIG. 21 is a development elevation showing flexible printed wiring boardused in the object lens drive device according to the present invention.

FIG. 22 is a perspective view showing the state where respectiveportions of flexible printed wiring board are attached to movableportion and fixed portion.

FIG. 23 is a cross sectional view showing object lens drive devicecompared to the object lens drive device according to the presentinvention.

FIG. 24 is a graph showing frequency response (the relationship betweenamplitude and frequency) when movable portion is operated in thefocusing direction.

FIG. 25 is a graph showing frequency response (the relationship betweenphase and frequency) when movable portion is operated in focusingdirection.

FIG. 26 is a graph showing frequency response (the relationship betweenamplitude and frequency) when the movable portion is operated intracking direction.

FIG. 27 is a graph showing frequency response (the relationship betweenphase and frequency) when movable portion is operated in trackingdirection.

FIG. 28 is a conceptual view for explaining the relationship betweenmagnetic member and flexible printed wiring board, and showing the statewhere the movable portion is held at the neutral position in focusingdirection.

FIG. 29 is a conceptual view showing the state where the movable portionis moved to one movement end in focusing direction.

FIG. 30 is a conceptual view showing the state where movable portion ismoved to the other movement end in focusing direction.

FIG. 31 is a conceptual view showing the state where movable portion isplaced at balance position.

FIG. 32 is a development elevation showing another example of flexibleprinted wiring board used in the object lens drive device according tothe present invention, and

FIG. 33 is an enlarged perspective view showing the state whererespective portions of that flexible printed wiring board are attachedto movable portion and fixed portion.

BEST MODE FOR CARRYING OUT THE INVENTION

An object lens drive device and a disc recording and/or reproducingapparatus using such an object lens drive device according to thepresent invention will now be described with reference to the attacheddrawings.

It is to be noted that explanation will be given in the followingexplanation by taking the example where the object lens drive deviceaccording to the present invention is applied to a disc drive unit(apparatus) in which optical disc is used as recording medium.

As shown in FIG. 1, the disc drive unit 1 in which the object lens drivedevice according to the present invention is used is adapted so that,within a thin box-shaped casing 2, there are provided a rotation drivemechanism for rotationally driving an optical disc 100, and mechanismsand/or electronic circuit units necessary for carrying out recording orreproduction (playback) of information signals with respect to theoptical disc 100 such as an optical pick-up 7, etc. for carrying outrecording of information signals with respect to the optical disc 100rotationally driven by this rotation drive mechanism and/or for carryingout read-out of information signals recorded on the optical disc 100 toconstitute the unit body.

At the front surface of the casing 2, as shown in FIG. 1, there isformed an insertion/withdrawal hole 2 a for carrying outinsertion/withdrawal of the optical disc 100. The insertion/withdrawalhole 2 a is formed so as to take laterally elongated rectangular shape.Within the casing 2, as shown in FIG. 1, a chassis 3 is disposed. At thelower surface side of substantially central portion of the chassis 3,there is disposed spindle motor (not shown) for rotationally driving theoptical disc 100. At the front end portion of the spindle shaft of thespindle motor, a disc table 4 is attached so that it is rotated in onebody. At the chassis 3, an arrangement hole 3 a for projecting the disctable 4 is formed. As shown in FIG. 1, the disc table 4 attached to thespindle shaft is projected from the arrangement hole 3 a toward theupper direction of the chassis 3.

At the lower surface side of the chassis 3, as shown in FIG. 1, a leadscrew 5 and a pair of guide shafts 6, 6 are arranged in the parallelstate. At the arrangement hole 3 a formed at the chassis 3, the opticalpick-up 7 is disposed in the state where it can be moved in the radialdirection of the optical disc 100 loaded on the disc table 4.

The optical pick-up 7 is adapted so that light source such assemiconductor laser, etc. and optical element for guiding light beansemitted from the light source to object lens, etc. are mounted on amovement base 8. At the optical pick-up 7, one end portion of themovement base 8 is screw-connected to the lead screw 5 and both endportions of the movement base 8 are respectively slidably supported bythe guide shafts 6, 6. The optical pick-up 7 is moved in the radialdirection of the optical disc 100 in a manner guided by the guide shafts6, 6 by rotation of the lead screw 5.

An object lens drive device 9 comprises, as shown in FIGS. 2 to 5, afixed portion 10 formed by magnetic metallic material, and a movableportion 11 supported by this fixed portion 10.

The fixed portion 10 includes, as shown in FIGS. 2 and 3, a base portion12 attached on the upper surface of the movement base 8, a pair of yokeportions 13, 13 formed in a manner bent respectively toward the upperdirection from both side edges of this base portion 12, and a supportingshaft 14 projected toward the upper direction substantially from thecentral portion of the base portion 12.

The yoke portion 13 is composed of an attachment portion 13 a, and bentportions 13 b, 13 b formed in the state bent so as to oppose the insidefrom both side edges before and after of this attachment portion 13 a.At the upper side of these bent portions 13 b, 13 b, engagementprojected portions 13 c, 13 c are formed in a projected manner.

At the internal surfaces of the respective yoke portions 13, 13, magnets15, 15 are respectively fixed. The magnets 15, 15 are adapted so thatsurfaces of the sides opposite to each other, i.e., surfaces of thesides opposite to the supporting shaft 14 are polarized (magnetized) sothat they have the same pole. The surfaces opposite to each other of therespective magnets 15, 15 are polarized (magnetized) so that they haveeither one of S-pole and N-pole. In this example, the surfaces oppositeto each other of the respective magnets 15, 15 are polarized(magnetized) so as to indicate S-pole. As shown in FIG. 2, the magnets15, 15 are adapted so that respective surfaces of both sidesperpendicular to the surface attached to the yoke portions 13, 13 arerespectively covered by the pair of bent portions 13 b, 13 b.

At a bobbin 16 of the movable portion 11, necessary respective memberssuch as a focusing coil 23 and tracking coils 24, 24, etc. are attached.

The bobbin 16 includes, as shown in FIG. 3, a body portion 17, and alens holder 19 projected toward the forward direction from this bodyportion 17. The body portion 17 includes an upper surface portion 17 a,side surface portions 17 b, 17 b projected toward lower direction fromboth side edges of this upper surface portion 17 a, and a back surfaceportion 17 c projected toward the lower direction from the rear edge ofthe upper surface portion 17 a, wherein a balancer attachment portion 17d is projected toward backward direction from the lower edge of the backsurface portion 17 c (see FIG. 5). Substantially at the central portionof the upper surface portion 17 a, a cylindrical supporting cylinder 17e projected toward lower direction is provided (see FIG. 5). Theinternal space of the supporting cylinder 17 e of the body portion 17 isused as a supporting hole 18 of the supporting shaft 14 (see FIG. 5).

A transmission hole 19 a is formed at the lens holder 19, and pluralholding projected portions 19 b are provided at the outer peripherythereof.

At the balancer attachment portion 17 d of the bobbin 16, as shown inFIGS. 3 and 5, a round shaft-shaped balancer 20 is attached.

At the lens holder 19 provided at the bobbin 16, as shown in FIG. 4, anobject lens 21 is held in the state where it is pressed and supportedfrom the periphery by plural holding projected portions 19 b.

At the lower surface of the upper surface portion 17 a of the bobbin 16,a coil body 22 is attached (see FIGS. 3 to 5). The coil body 22comprises the focusing coil 23 wound substantially in rectangularcylindrical form so that the axial direction is upper and lowerdirections, and the tracking coils 24, 24 by one pair which are attachedto side surfaces opposite to each other of this focusing coil 23 in thestate where they are adjacent to each other and are in parallel witheach other before and after.

At the supporting cylinder 17 e of the bobbin 16, a magnetic member 25formed to be substantially annular by linear magnetic metallic materialis attached (see FIGS. 3 to 5). In this example, as shown in FIG. 3, themagnetic member 25 is formed so as to take annular shape where a portionis opened. Namely, the magnetic member 25 includes a connecting portion25 b curved to be semi-circular of the central portion, and a pair ofend portions 25 c, 25 c extended from both ends of this connectingportion 25 b. The magnetic member 25 is formed to be annular by bendingend portions 25 c, 25 c so that they are close to each other to extendthem from both ends of the connecting portion 25 b. At the magneticmember 25 formed to be annular in this way, connecting portions to theconnecting portion 25 b of the end portions 25 c, 25 c are caused to beprojected portions 25 a, 25 a bent so as to project toward both sides.These pair of projected portions 25 a, 25 a are formed in a mannerprojected toward the external from circle serving as center of themagnetic member 25 formed to be annular. Namely, at the magnetic member25, the respective projected portions 25 a, 25 a are formed to beannular in the state bent in a manner projected toward the sidedirection, whereby distance between the pair of projected portions 25 a,25 a becomes maximum. Thus, the magnetic member 25 is caused to haveshape in which these projected portions 25 a, 25 a are placed at theoutermost side.

As shown in FIGS. 4 and 5, the magnetic member 25 is fitted and disposedat the outer periphery of the supporting cylinder 17 e in the statewhere the connecting portion 25 b is positioned at the lens holder 19side where the object lens 21 is attached, and the pair of projectedportions 25 a, 25 a are positioned at both sides of the supportingcylinder 17 e. At this time, the magnetic member 25 is attached to thesupporting cylinder 17 e in the forward rising state inclined so thatthe connecting portion 25 b is positioned at the front end side of thesupporting shaft 14 which is the upper side from the end portions 25 c,25 c of the opening side. At this time, at the magnetic member 25, asshown in FIG. 4, the respective projected portions 25 a, 25 a are placedin the state where they are closest to the respective magnets 15, 15 ofboth sides. As shown in FIG. 6, the magnetic member 25 fitted anddisposed at the outer periphery of the supporting cylinder 17 e in thisway is adapted so that its center axis 25 d is inclined by angle θtoward the backward side of the side opposite to the lens holder 19 withrespect to center axis 18 a of the supporting hole 18.

As the result of the fact that the supporting shaft 14 is inserted intothe supporting hole 18, the movable portion 11 is supported slidably inthe axial direction of the supporting shaft 14 and rotatably in thedirection about the axis of the supporting shaft 14 (see FIGS. 2, 4 and5). The axial direction of the supporting shaft 14 is the focusingdirection where the position of the object lens 21 is controlled so thatlight beams irradiated through the object lens 21 are irradiated ontothe signal recording surface of the optical disc 100 in focus state, andthe direction about the axis of the supporting shaft 14 is the trackingdirection where light beams irradiated through the object lens 21 followrecording tracks of the optical disc 100.

In the state where the movable portion 11 is supported at the supportingshaft 14, as shown in FIGS. 2 and 4, the magnets 15, 15 are positionedin the state close to the outside of respective side surface portions 17b, 17 b of the bobbin 16 and opposite thereto. In the state where themovable portion 11 is supported by the supporting shaft 14, as shown inFIG. 5, one end portion 26 a of a flexible printed wiring board 26 isattached to the bobbin 16, and the other end portion 26 b of theflexible printed wiring board 26 is attached to the base portion 12 ofthe fixed portion 10. The one end portion 26 a of the flexible printedwiring board 26 attached to the bobbin 16 is electrically connected tothe focusing coil 23 and the respective tracking coils 24, and the otherend portion 26 b of the flexible printed wiring board 26 attached to thebase portion 12 is connected to drive circuit (not shown) for operatingthe object lens drive device 9.

At the fixed portion 10, a cover 27 which covers the movable portion 11is attached (see FIGS. 2, 3 and 5). The cover 27 is adapted so that atop plate 28 and side plates 29, 29 projected toward the lower directionfrom left and right both side edges of the top plate 28 are integrallyformed by magnetic metallic material, and plural engagement holes 27 aare formed in a manner spaced before and after at the portion where thetop plate 28 and the side plate portions 29, 29 are continuous. Thecover 27 is attached to the fixed portion 10 as the result of the factthat engagement projected portions 13 c provided at the fixed portion 10are respectively engaged with the respective engagement holes 27 a (seeFIG. 2).

Then, explanation will be given in connection with the operation inwhich the optical disc 100 is loaded with respect to the disc drive unit1 using the above-described object lens drive device 9 to carry outrecording or reproduction of information signals.

In order to record information signals onto the optical disc 100 or toreproduce information signals recorded on the optical disc 100, theoptical disc 100 is loaded with respect to the disc table 4. At the timepoint when the optical disc 100 is loaded with respect to the disc table4, recording switch or reproduction switch (not shown) is operated. Whenthe recording switch or the reproduction switch is operated, the spindlemotor is driven. Thus, the disc table 4 is rotated in one body with theoptical disc 100. When the optical disc 100 is rotated, light beams areemitted from light emitting element like semiconductor laser provided atthe movement base 8, and are irradiated onto the signal recordingsurface of the optical disc 100 through the object lens 21.

Light beams which have been irradiated onto the signal recording surfaceof the optical disc 100 are reflected by the signal recording surface,and are incident on light receiving element provided at the movementbase 8, at which they are caused to undergo photoelectric conversion.Thus, recording or reproduction of information signals is carried out.

When recording or reproduction of information signals is carried out,light beams are irradiated onto the signal recording surface of theoptical disc 100 in the in-focus state. Thus, focusing control andtracking control of the object lens 21 are carried out by the objectlens drive device 9 in a manner to follow recording tracks. At the timeof focusing control, the movable portion 11 is slid in the axialdirection of the supporting shaft 14 so that beam spot of light beamsirradiated through the object lens 21 is irradiated onto the recordingsurface of the optical disc 100 in the in-focus state. At the time oftracking control, the movable portion 11 is rotated in the directionabout the axis of the supporting shaft 14 so that beam spot of lightbeams irradiated through the object lens 21 is caused to be in-focusstate on recording tracks of the optical disc 100.

The movable portion 11 is held at the neutral position in the focusingdirection and in the tracking direction in the inoperative state whereit is not driven in both directions of the focusing direction and thetracking direction. Namely, at the movable portion 11, in theinoperative state, the respective projected portions 25 a, 25 a closestto the respective magnets 15, 15 projected toward both sides of themagnetic member 25 fitted and disposed at the supporting cylinder 17 eare attracted by the respective magnets 15, 15 so that they are held atthe neutral position in the tracking direction. Further, at the magneticmember 25, the connecting portion 25 b is attached in the state inclinedby angle θ with respect to the supporting cylinder 17 e in a mannerpositioned at the front end side of the supporting shaft 14, whereby theconnecting portion 25 b is attracted toward the cover 27 side by actionof magnetic field produced from the respective magnets 15, 15. As aresult, the end portions 25 c, 25 c of the opening side are attractedtoward the base portion 12 side, and are held in the state rotated inthe direction indicated by arrow M in FIG. 7. Namely, the movableportion 11 is held at the neutral position in the focusing directionwhere the movable portion 11 is supported in the state where it isinclined with respect to the supporting shaft 14 and a portion of upperand lower opening ends of the supporting hole 18 is caused to be incontact with the outer circumferential surface of the supporting shaft14. At this time, angular moment (rotation torque) in the directionindicated by arrow M in FIG. 7 is operated (worked) by action ofmagnetic field produced from the respective magnets 15, 15 with respectto the movable portion 11.

The object lens drive device 9 according to the present inventionundergoes angular moment in the direction indicated by arrow M in FIG. 7to move the movable portion 11 placed in the state inclined by angle θwith respect to the supporting shaft 14 in the axial direction of thesupporting shaft 14 while it is in the inclined state to carry out focuscontrol, and to rotate the movable portion 11 in the direction about theaxis of the supporting shaft 14 to carry out tracking control. Namely,the movable portion 11 is moved in the focusing direction and is rotatedin the tracking direction in the state where the supporting shaft 14 issupported by two points of upper and lower opening ends of thesupporting hole 18.

Here, the relationship between inclination angle with respect to thesupporting hole 18 provided at the movable portion 11 where the magneticmember 25 is attached of the magnetic member 25 formed to be annular inthe state where a portion thereof is opened as described above andangular moment (rotation torque) produced at respective portions of themagnetic member 25 is measured. As shown in FIG. 8, measurements ofangular moment were carried out at portion a of the connecting portion25 b of the magnetic member 25, portions b, d in the vicinity ofprojected portions 25 a, 25 a of the both sides, and portions c, e ofend portions 25 c, 25 c of the opening side. The result of themeasurement thereof is shown in FIG. 9.

In FIG. 9, the abscissa indicates inclination angle θ of center axis 25d of the magnetic member 25 with respect to central axis 18 a of thesupporting hole 18, wherein plus (+) indicates the state where theconnecting portion 25 b side is inclined in a manner positioned at thefront end side of the supporting shaft 14, and minus (−) indicates thestate where the connecting portion 25 b side is inclined in a mannerpositioned at the base end portion side of the supporting shaft 14. Theordinate of FIG. 9 indicates value of angular moment (rotation torque).

As shown in FIG. 9, rotation torque produced at the portion a of theconnecting portion 25 b indicates the characteristic as indicated by Ain FIG. 9, rotation torques produced at the portions b, d in thevicinity of projected portions 25 a, 25 a of the both sides indicate thecharacteristics indicated by B, D in the figure, and rotation torquesproduced at the portions c, e of end portions 25 c, 25 c of the openingside indicate the characteristics as indicated by C, E in the figure.

From the result of the measurement shown in FIG. 9, it has beenunderstood that it is desirable that inclination angle θ of the magneticmember 25 with respect to the supporting hole 18 is 20° to 40° (alsoincluding −20° to −40°) in order that satisfactory slidability of themovable portion 11 with respect to the supporting shaft 14 can beenhanced, and the movable portion 11 can hold the state inclined in apredetermined direction with respect to the supporting shaft 14 at alltimes.

FIGS. 10 to 12 are graphical diagrams showing the result in which therelationship between position in the focusing direction of the movableportion 11 and inclination angle with respect to the supporting shaft 14of the movable portion 11 when the movable portion 11 is placed inseveral installation states is measured. These measurements are carriedout in the state where the magnetic member 25 is lowered backwardly withrespect to the supporting hole 18, i.e., in the state where theconnecting portion 25 b side is inclined by 30° in a manner positionedat the front end side of the supporting shaft 14. Respectivemeasurements are carried out in the following three states. Namely,measurements are carried out in connection with the state of neutralposition (Tr=0.0000 mm) where the movable portion 11 is not operated inthe tracking direction, the state where the movable portion 11 isrotated by a predetermined quantity in one direction with the supportingshaft 14 being as center from the neutral position so that the opticalaxis of the object lens 21 is rotated by, e.g., 0.2500 mm from theneutral position, and the state where the movable portion 11 is rotatedby a predetermined quantity toward the other direction with thesupporting shaft 14 being as center from the neutral position so thatthe optical axis of the object lens 21 is rotated by, e.g., 0.2500 mmfrom the neutral position.

The abscissa in FIGS. 10 to 12 indicates position in the focusingdirection of the movable portion 11, wherein “0” indicates neutralposition, plus (+) indicates the position moved to the front end side ofthe supporting shaft 14, and minus (−) indicates the position moved tothe base end portion side of the supporting shaft 14. Measurement iscarried out within the measurement range (from −0.6 mm to 0.6 mm) in thefocusing direction of the movable portion 11. The ordinate in therespective figures indicates inclination angle with respect to thesupporting shaft 14 of the movable portion 11. With respect to thisinclination angle, reference angle when the movable portion 11 is placedat the neutral position is caused to be “0”.

P in FIGS. 10 to 12 indicates the characteristic when the movableportion 11 is located at the neutral position, S indicates thecharacteristic when the movable portion 11 is rotated in one directionwith the supporting shaft 14 being as center, and T indicates thecharacteristic when the movable portion 11 is rotated in the otherdirection with the supporting shaft 14 being as center.

FIG. 10 is the result in which measurement is carried out in the statewhere the axial direction of the supporting shaft 14 is verticaldirection, FIG. 11 is the result in which measurement is carried out inthe state where the axial direction of the supporting shaft 14 ishorizontal direction and the object lens 21 is located at the lowerportion of the supporting shaft 14, and FIG. 12 is the result in whichmeasurement is carried out in the state where the axial direction of thesupporting shaft 14 is horizontal direction and the object lens 21 islocated at the side direction of the supporting shaft 14.

FIGS. 13 to 15 are graphical diagrams showing the result in which therelationship between position in the focusing direction of the movableportion 11 and inclination angle with respect to the supporting shaft 14of the movable portion 11 when movable portion 11 of the configurationsimilar to the movable portion in the conventional object lens device isplaced in several installation states is measured. These measurementsare carried out in the state where the magnetic member 25 is notinclined with respect to the supporting hole 18, i.e., an angle that thecenter axis of the supporting hole 18 and center axis of the magneticmember 25 form is equal to 0°. Similarly to the above-described presentinvention, these measurements are also carried out in connection withthe state of the neutral position where the movable portion 11 is notoperated in the tracking direction (Tr=0.0000 mm), the state where themovable portion 11 is rotated by a predetermined quantity in onedirection with the supporting shaft 14 being as center from the neutralposition so that the optical axis of the object lens 21 is rotated by,e.g., 0.2500 mm from the neutral position, and the state where themovable portion 11 is rotated by a predetermined quantity in the otherdirection with the supporting shaft 14 being as center from the neutralposition so that the optical axis of the object lens 21 is rotated by,e.g., 0.2500 mm from the neutral position.

The abscissa and the ordinate of FIGS. 13 to 15 are the same as those ofrespective views of FIGS. 10 to 12.

P′ in FIGS. 13 to 15 indicates the characteristic when the movableportion 11 is located at the neutral position, S′ indicates thecharacteristic when the movable portion 11 is rotated in one directionwith the supporting shaft 14 being as center, and T′ indicates thecharacteristic when the movable portion 11 is rotated in the otherdirection with the supporting shaft 14 being as center.

As the result of these measurements, in the object lens drive device 9according to the present invention, it has been confirmed that, ascompared to the conventional object lens drive device, there hardlyexists change in direction of inclination of the movable portion 11 whenthe movable portion 11 is operated in the focusing direction, and themovable portion 11 is operated in the state inclined in a predetermineddirection at all times with respect to the supporting shaft 14.

As described above, in the object lens drive device 9 according to thepresent invention, since the magnetic member 25 is attached to themovable portion 11 in the state inclined with respect to the supportinghole 18, the movable portion 11 is operated in the state inclined in apredetermined direction with respect to the supporting shaft 14 at alltimes. Accordingly, when the movable portion 11 is operated, there is nopossibility that change takes place in direction of inclination withrespect to the supporting shaft 14 of the movable portion 11 to haveability to ensure the stable operating state of the movable portion 11.Since the movable portion 11 is operated in the state where angularmoment in a predetermined direction is produced at all times, it ispossible to ensure the stable operating state irrespective of change ofattitude of the movable portion 11. Since there is no change indirection of inclination with respect to the supporting shaft 14 of themovable portion 11, it is possible to shorten length of the supportinghole 18. Thus, the object lens drive device 9 caused to be of thinstructure can be realized.

In the object lens drive device according to the present invention, themovable portion 11 is inclined in a manner inclined by a predeterminedangle θ with respect to the supporting shaft 14, whereby center O ofline L, which connects two contact points X₁, X₂ of two opening edges ofthe supporting hole 18 of the movable portion 11 and the supportingshaft 14 with which these opening edges are in contact is positioned oncenter axis 14 a of the supporting shaft 14 as shown in FIG. 7.Accordingly, balance of the movable portion 11 with respect to thesupporting shaft 14 is satisfactory. Thus, it is possible tosatisfactorily maintain the characteristics of the focus control and thetracking control of the object lens drive device 9.

In addition, since annular member in which one end is opened is used asthe magnetic member 25, the configuration of the magnetic member issimple, and it is also possible to extremely easily carry out attachmentwith respect to the supporting cylinder 17 e of the movable portion 11.

While the magnetic member 25 is attached to the supporting cylinder 17 ein the state where center axis 25 d is inclined backwardly with respectto center axis 18 a of the supporting hole 18, i.e., in a manner suchthat connecting portion 25 b is positioned at the front end side of thesupporting shaft 14 in the movable portion 11 of the above-describedobject lens drive device 9, the magnetic member 25 may be attached tothe supporting cylinder 17 e, in a manner opposite to the above, in thestate where center axis 25 d is inclined forwardly with respect tocenter axis 18 a of the supporting hole 18, i.e., in such a manner thatconnecting portion 25 b is positioned at the base end portion side ofthe supporting shaft 14.

While magnetic member formed as an annular member where a portion isopened is used as the magnetic member 25, there may be used a magneticmember formed as a closed annular member where a portion is not opened.Even in the case where such magnetic member 25 is used, the upper sideportion of the connecting portion 25 b side is attracted toward theupper side by action of magnetic field of the magnets 15, 15constituting magnetic circuit, and the closed portion of the lower sideopposite to the connecting portion 25 b is attracted toward lowerdirection. Accordingly, since the magnetic member 25 can undergo angularmoment rotated in one direction with respect to the supporting shaft 14,action (function) similar to the above can be realized.

Then, another embodiment of the present invention will be explained withreference to the attached drawings.

An object lens drive device which will be explained below is also usedin optical pick-up 7 assembled in the disc drive apparatus 1 constitutedas shown in FIG. 1.

The object lens drive device 109 used in this optical pick-up 7comprises, as shown in FIGS. 16 to 20, a fixed portion 110 formed bymagnetic metallic material, and a movable portion 111 supported at thisfixed portion 110.

The fixed portion 110 includes, as shown in FIGS. 16 and 17, a baseportion 112 attached on the upper surface of a movement base 108, a pairof yoke portions 113, 113 formed in a manner respectively bent towardupper direction from both side edges of this base portion 112, and asupporting shaft 114 projected upwardly from substantially the centralportion of the base portion 112.

The yoke portion 113 is comprised of attachment portions 113 a, and bentportions 113 b, 113 b formed in a bent form so as to oppose the insidefrom both side edges before and after of the attachment portions 113 a.At the upper side of these bent portions 113 b, 113 b, there are formedengagement projected portions 113 c, 113 c in a projected manner.

At the internal surfaces of the respective yoke portions 113, 113,magnets 115, 115 are respectively fixed. The magnets 115, 115 areadapted so that surfaces of the sides opposite to each other, i.e.,surfaces of the sides opposite to the supporting shaft 114 are polarized(magnetized) so that they both have the same pole. The surfaces oppositeto each other of the respective magnets 115, 115 are polarized(magnetized) so that they have either S-pole or N-pole. In this example,the surfaces opposite to each other of the respective magnets 115, 115are polarized (magnetized) so that they have S-pole. At the magnets 115,115, as shown in FIG. 16, respective surfaces of both sidesperpendicular to the surfaces respectively attached to the yoke portions113, 113 are covered by the pair of bent portions 113 b, 113 b.

At a bobbin 116 of the movable portion 111, there are attached necessaryrespective members such as a focusing coil 123 and tracking coils 124,124, etc.

The bobbin 116 includes, as shown in FIG. 17, a body portion 117 and alens holder 119 forwardly projected from this body portion 117. The bodyportion 117 includes an upper surface portion 117 a, side surfaceportions 117 b, 117 b projected toward the lower direction from bothside edges of this upper surface portion 117 a, and a backward surfaceportion 117 c projected toward lower direction from the rear edge of theupper surface portion 117 a, wherein a base attachment portion 117 d isprojected toward the backward direction from the lower edge of thebackward surface portion 117 c (see FIG. 19). At the central portion inleft and right directions of the backward end side of the baseattachment portion 117 d, there is formed a slit 117 e for insertionwhich is opened toward the backward direction. Substantially at thecentral portion of the upper surface portion 117 a, there is provided acylindrical supporting cylinder 117 f projected toward the lowerdirection (see FIG. 19). The internal space of the supporting cylinder117 f of the body portion 117 is used as a supporting hole 118 of thesupporting shaft 114 (see FIG. 19).

At a lens holder 119, there is formed a transmission hole 119 a. Pluralholding projected portions 119 b are provided at the outer periphery.

At the base attachment portion 117 d of the bobbin 116, as shown inFIGS. 19 and 20, there is attached a round shaft shaped balancer 120.

At the lens holder 119 provided at the bobbin 116, as shown in FIG. 18,an object lens 121 is held in the state where it is pressed andsupported from the periphery at the plural holding projected portions119 b.

At the lower surface of the upper surface portion 117 a of the bobbin116, a coil body 122 is attached (see FIGS. 17 to 19). The coil body 122comprises the focusing coil 123 wound in substantially rectangularcylindrical form so that the axial direction is caused to be upper andlower directions, and tracking coils 124, 124 by one pair which areattached in the state adjacent to each other and in parallel to eachother before and after at side surfaces opposite to each other of thisfocusing coil 123.

At the supporting cylinder 117 f of the bobbin 116, a magnetic member125 formed to be substantially annular by linear magnetic metallicmaterial is attached (see FIGS. 17 to 19). As shown in FIG. 17, themagnetic member 125 is formed so as to take annular shape in which aportion is opened. Namely, the magnetic member 125 includes a connectingportion 125 b curved so as to take semi-circular shape at the centralportion, and a pair of end portions 125 c, 125 c extended from both endsof this connecting portion 125 b. The magnetic member 125 is formed tobe annular as the result of the fact that end portions 125 c, 125 c arebent so that they are close to each other and are extended from bothends of the connecting portion 125 b. The magnetic member 125 formed tobe annular in this way is adapted so that the connecting portion to theconnecting portion 125 b of the end portions 125 c, 125 c is caused tobe projected portions 125 a, 125 a bent so as to project toward the bothsides. These pair of projected portions 125 a, 125 a are formed so thatthey are projected toward the external from circle serving as center ofthe magnetic member 125 formed to be annular.

As the result of the fact that the supporting shaft 114 is inserted intothe supporting hole 118, the movable portion 111 is supported slidablyin the axial direction of the supporting shaft 114 and rotatably in thedirection about the axis of the supporting shaft 114 (see FIGS. 16, 18and 19). The axial direction of the supporting shaft 114 is the focusingdirection of F-F direction in FIGS. 16, 19 and 20 where position of theobject lens 121 is controlled so that light beams irradiated through theobject lens 121 are irradiated onto the signal recording surface of theoptical disc 100 in the in-focus state, and the direction about the axisof the supporting shaft 114 is the tracking direction of T-T directionin FIGS. 16, 18 and 20 where control is conducted so that light beamsirradiated through the object lens 121 follow recording tracks of theoptical disc 100.

In the state where the movable portion 111 is supporting by thesupporting shaft 114, as shown in FIGS. 16 and 18, the magnets 115, 115are positioned in a manner close to the outside of respective sidesurface portions 117 b, 117 b and opposite thereto of the bobbin 116. Inthe state where the movable portion 111 is supported by the supportingshaft 114, as shown in FIGS. 17, 19 and 20, a portion of a flexibleprinted wiring board 126 is attached in a manner bridging over the fixedportion 110 and the movable portion 111.

The flexible printed wiring board 126 is adapted so that the base isformed by material having flexibility, and includes, as shown in FIGS.21 and 22, an attachment portion 127 attached to the fixed portion 110,a derivation portion 128 projected from this attachment portion 127, afirst junction portion 129, and a second junction portion 130. At theattachment portion 127, there is formed a hole 127 a.

The derivation portion 128 is formed in a manner elongated substantiallyin a predetermined direction, and is adapted so that four land portions128 a for circuit are provided at the front end portion in a mannerspaced from each other when viewed in the developed state as shown inFIG. 21.

When viewed in the developed state as shown in FIG. 21, the firstjunction portion 129 is formed in such a manner that it is projectedfrom the attachment portion 127 in the state spaced from the derivationportion 128 in the same direction as that of the derivation portion 128,and the front end portion thereof is bent perpendicular to thehorizontal direction. At the front end portion of the first junctionportion 129, land portions 129 a, 129 a for coil for carrying outconnection to the tracking coil are provided in the state spaced fromeach other.

When viewed in the developed state as shown in FIG. 21, the secondjunction portion 130 is formed in such a manner that it is projectedfrom the attachment portion 127 in the direction opposite to the firstjunction portion 129, and the front end portion thereof is bentperpendicular to the horizontal direction so as to project in the samedirection as that of the front end portion of the first junction portion129. At the front end portion of the second junction portion 130, landportions 130 a, 130 a for coil for carrying out connection to thefocusing coil are provided in the state spaced from each other.

Land portions 129 a, 129 a to which the tracking coils are connected andland portions 130 a, 130 a to which the focusing coil is connected areboth formed at the lower surface side when viewed in the developmentelevation shown in FIG. 21.

At the flexible printed wiring board 126, as shown in FIG. 21, there areformed four circuit patterns 131, 131, 132, 132. The circuit patterns131, 131 are circuit patterns electrically connected to one coil, e.g.,tracking coil 124, and are respectively formed between land portions 128a, 128 a for circuit and land portions 129 a, 129 a for coil. Suchcircuit patterns extend to land portions 129 a, 129 a for coil via thederivation portion 128, the attachment portion 127 and the firstjunction portion 129 from land portions 128 a, 128 a for circuit. Thecircuit patterns 132, 132 are circuit patterns electrically connected tothe other coil, e.g., focusing coil 123, and are respectively formedbetween land portions 128 a, 128 a for circuit and land portions 130 a,130 a for coil. Such circuit patterns extend to land portions 130 a, 130a for coil via the derivation portion 128, the attachment portion 127and the second junction portion 130 from the land portions 128 a, 128 afor circuit.

The flexible printed wiring board 126 is attached in such a manner thatthe first junction portion 129 and the second junction portion 130bridge over the fixed portion 110 and the movable portion 111 (see FIGS.16 to 20).

The flexible printed wiring board 126 is adapted so that the attachmentportion 127 is attached to the lower surface of the base portion 112 ofthe fixed portion 110 (see FIGS. 19 and 20). The supporting shaft 114 isslightly projected toward the lower direction from the lower surface ofthe base portion 112, and the attachment portion 127 is attached to thebase portion 112 in the state where the lower end portion of thesupporting shaft 114 is inserted into the hole 127. The first junctionportion 129 and the second junction portion 130 are adapted so that theportion curved so as to take substantially circular shape and close tothe front end is inserted into the slit 117 e for insertion of themovable portion 111 in the state in contact therewith, and the portionwhere the land portions 129 a, 129 a for coil are formed and the portionwhere the land portions 130 a, 130 a for coil are formed are bonded, by,e.g., double-faced tape, at the lower surface of the base attachmentportion 117 d in the state bent in directions opposite to each other(see FIGS. 19 and 20). At this time, the portion close to the front endof the first junction portion 129 and the second junction portion 130 ofthe flexible printed wiring board 126 is inserted into the slit 117 efor insertion, and the portion where the land portions 129 a, 129 a forcoil are formed and the portion where the land portions 130 a, 130 a forcoil are formed are only bent in directions opposite to each other tohave ability to carry out adhesion toward the lower surface of the baseattachment portion 117 d. For this reason, it is possible to extremelyeasily carry out attachment with respect to the movable portion 111 ofthe flexible printed wiring board 126.

In the state where the flexible printed wiring board 126 is attached inthis way, both end portions of the tracking coil 124 are respectivelyconnected to the land portions 129 a, 129 a for coil by soldering, andboth end portions of the focusing coil 123 are respectively connected tothe land portions 130 a, 130 a for coil by soldering.

In the state where the flexible printed wiring board 126 is attached tothe base attachment portion 117 d, the land portions 129 a, 129 a forcoil to which the tracking coils are connected and the land portions 130a, 130 a for coil for focusing coil are both directed to the baseportion 112 side. For this reason, it is possible to easily solder bothend portions of the tracking coil 124 and both end portions of thefocusing coil 123 with respect to land portions 129 a, 129 a for coil.

As shown in FIGS. 16 and 18, the derivation portion 128 of the flexibleprinted wiring board 126 is projected toward the side direction from thefixed portion 110, and the land portions 128 a for circuit arerespectively connected to respective terminal portions of current supplycircuit.

The flexible printed wiring board 126 attached as described above isdisposed so that width directions of the first junction portion 129 andthe second junction portion 130 are perpendicular to the focusingdirection, and are perpendicular to the tracking direction (see FIGS.16, 18, 19 and 20). The first junction portion 129 and the secondjunction portion 130 of the flexible printed wiring board 126 aresymmetrically disposed with the plane surface including optical axis 121a of the object lens 121 and central axis 114 a of the supporting shaft114 being as reference (see FIGS. 18 to 20).

At the fixed portion 110, a cover 133 which covers the movable portion111 is attached (see FIGS. 16, 17 and 19). The cover 133 is adapted sothat a top plate 134 and side plates 135, 135 projected toward lowerdirection from left and right both side edges of the top plate 134 areintegrally formed by magnetic metallic material, and plural engagementholes 133 a are formed in a manner spaced before and after at thecontinuous portion of the top plate 134 and the side plate portions 135,135. The cover 133 is attached to the fixed portion 110 as the result ofthe fact that engagement projected portions 113 c provided at the fixedportion 110 are respectively engaged with the respective engagementholes 133 a (see FIG. 16).

Then, explanation will be given in connection with the operation inwhich the optical disc 100 is loaded with respect to the disc drive unit1 using the above-described object lens drive device 109 to carry outrecording or reproduction of information signals.

In order to record information signals onto the optical disc 100 or tocarry out reproduction of information signals recorded on the opticaldisc 100, the optical disc 100 is loaded with respect to the disc table4. At the time point when the optical disc 100 is loaded with respect tothe disc table 4, recording switch or reproduction switch (not shown) isoperated. When the recording switch or the reproduction switch isoperated, the spindle motor is driven. Thus, the disc table 4 is rotatedin one body with the optical disc 100. When the optical disc 100 isrotated, light beams are emitted from light emitting element likesemiconductor laser provided at the movement base 8, and are irradiatedonto the signal recording surface of the optical disc 100 through theobject lens 121.

The light beams irradiated onto the signal recording surface of theoptical disc 100 are reflected by the signal recording surface, and areincident on light receiving element provided at the movement base 8. Thelight beams thus incident are caused to undergo photo-electricconversion. Thus, recording or reproduction of information signals iscarried out.

When recording or reproduction of information signals is carried out,light beams are irradiated onto the signal recording surface of theoptical disc 100 in the in-focus state. Thus, focusing control andtracking control of the object lens 121 are carried out by the objectlens drive device 109 so as to follow recording tracks. At the time offocusing control, the movable portion 111 is slid in the axial directionof the supporting shaft 114 so that beam spot of light beams irradiatedthrough the object lens 121 is irradiated onto the recording surface ofthe optical disc 100 in the in-focus state. At the time of trackingcontrol, the movable portion 111 is rotated in the direction about theaxis of the supporting shaft 114 so that beam spot of light beamsirradiated through the object lens 121 is caused to be in-focus state onrecording tracks of the optical disc 100.

In the inoperative state where the movable portion 111 is not drivenboth in the focusing direction and in the tracking direction, it is heldat the neutral position in the focusing direction and in the trackingdirection. Namely, in the inoperative state, as the result of the factthat respective projected portions 125 a, 125 a closest to therespective magnets 115, 115 projected toward both sides of the magneticmember 125 fitted and arranged at the supporting cylinder 117 f areattracted by the respective magnets 115, 115, the movable portion 111 isheld at the neutral position in the tracking direction. Further, themagnetic member 125 is attached in the state inclined by a predeterminedangle θ with respect to the supporting cylinder 117 f in such a mannerthat the connecting portion 125 b is positioned at the front end side ofthe supporting shaft 114, whereby the connecting portion 125 b isattracted toward the cover 133 side by action of magnetic field producedfrom the respective magnets 115, 115, and end portions 125 c, 125 c ofthe opening side are attracted toward the base portion 112 side. Thus,the connecting portion 125 b is held in the state rotated toward thecover 133 side. Namely, the movable portion 111 is inclined with respectto the supporting shaft 114, and is held at the neutral position in thefocusing direction supported in the state where a portion of upper andlower opening ends of the supporting hole 118 is caused to be in contactwith the outer circumferential surface of the supporting shaft 114.

As described above, the object lens drive device 109 of this example isdisposed in such a manner that width direction of the first junctionportion 129 and the second junction portion 130 of the flexible printedwiring board 126 is perpendicular to the focusing direction and isperpendicular to the tracking direction. When the movable portion 111 isrespectively moved and rotated in the focusing direction of the axialdirection of the supporting shaft 114 and in the tracking direction ofthe direction about the axis of the supporting shaft 114, load withrespect to the movable portion 111 by rigidity of the flexible printedwiring board 126 is small so that improvement in the sensitivity of themovable portion 111 is realized. As a result, precise focus controlcorresponding to focus error signal is realized. Further, precisetracking control corresponding to tracking error signal is realized.

It is unnecessary to elongate length of the flexible printed wiringboard 126 in order to lessen load with respect to the movable portion111 by the flexible printed wiring board 126. Miniaturization of theobject lens drive device 109 can be realized accordingly.

Since the first junction portion 129 and the second junction portion 130of the flexible printed wiring board 126 are symmetrically disposed withthe plane surface including optical axis 121 a of the object lens 121and center axis 114 a of the supporting shaft 114 being as center, it ispossible to stably hold the movable portion 111 at the neutral positionin the tracking direction.

In the object lens drive device 109 of this example, at the firstjunction portion 129 and the second junction portion 130 of the flexibleprinted wiring board 126, there are respectively separately formedcircuit patterns 131, 131 in which drive current corresponding totracking error signal is delivered at the time of tracking control, andcircuit patterns 132, 132 in which drive current corresponding to focuserror signal is delivered at the time of focusing control. For thisreason, in the first junction portion 129 and the second junctionportion 130, it is possible to mutually lessen influence of noise.

Here, response characteristic when the movable portions where objectlenses of the object lens drive device 109 of this example and theobject lens drive device preceding to the present invention are attachedare caused to undergo movement displacement in the focusing directionand in the tracking direction will be considered in a comparativemanner.

Here, an object lens drive device 209 compared to the object lens drivedevice 109 according to the present invention is constituted as shown inFIG. 23. It is to be noted that common reference numerals arerespectively attached to the portions common to the object lens drivedeice 109 of the present invention, and the detailed explanation will beomitted.

In the object lens drive device 209 compared to the object lens drivedevice 109 of the present invention, as shown in FIG. 23, a flexibleprinted wiring board 226 which electrically connects a fixed portion 210and a movable portion 211 is adapted so that one end portion 227 isattached to the backward surface portion of bobbin 116 constituting themovable portion 211 in the state where the movable portion 211 issupported by supporting shaft 114, and an intermediate portion 228 ofthe flexible printed wiring board 226 is attached to the lower surfaceof an attachment portion 230 of the fixed portion 210. The other endportion (not shown) of the flexible printed wiring board 226 isconnected to current supply circuit (not shown). The flexible printedwiring board 226 is disposed in the curved state so that width directionof a junction portion 231, serving as the portion which connects thefixed portion 210 and the movable portion 211 is caused to be incorrespondence with the tracking direction.

One end portion 227 of the flexible printed wiring board 226 attached tothe bobbin 116 is electrically connected to the focusing coil 123 andthe tracking coils 124, and currents are respectively delivered fromcurrent supply circuit to the focusing coil 123 and the tracking coils124 through the flexible printed wiring board 226.

The object lens drive device 209 shown in FIG. 23 is attached to thefixed portion 210 and the movable portion 211 in such a manner thatwidth direction of a junction portion 231 of the flexible printed wiringboard 226 is caused to be in correspondence with the tracking directionwhere the movable portion 211 is rotated in the direction about theperiphery of the supporting shaft 114. Accordingly, when the movableportion 211 is operated in the tracking direction, large load is apt tobe applied to the movable portion 211 by rigidity of the flexibleprinted wiring board 226, and there is the possibility that obstacle maytake place particularly in the operation in the tracking direction ofthe movable portion 211.

In this example, annular magnetic member 125 is attached in thehorizontal direction perpendicular to the axial direction of thesupporting shaft 114.

FIG. 24 is a graph indicating frequency response particularly therelationship between amplitude (gain) and frequency when the movableportion 211 or the movable portion 111 is operated in the focusingdirection with respect to the object lens drive device 209 shown in FIG.23 and the object lens drive device 109 according to the presentinvention. E in FIG. 24 is measured value with respect to the objectlens drive device 209 shown in FIG. 23, and F in FIG. 24 is measuredvalue with respect to the object lens drive device 109 according to thepresent invention.

FIG. 25 is a graph showing frequency response, particularly therelationship between phase and frequency when the movable portion 211 orthe movable portion 111 is operated in the focusing direction withrespect to the object lens drive device 209 shown in FIG. 23 and theobject lens drive device 109 according to the present invention. G inFIG. 25 is measured value with respect to the object lens drive device209 shown in FIG. 23, and H in FIG. 25 is measured value with respect tothe object lens drive device 109 according to the present invention.

As the result of the measurement, in the relationship between amplitudeand frequency, as shown in FIG. 24, in the object lens drive device 209shown in FIG. 23 and the object lens drive device 109 according to thepresent invention, large difference could not be observed. However, inthe relationship between phase and frequency shown in FIG. 25, there wasthe result that, in the lower frequency region, the frequency regionindicating inverting of phase is broad in the object lens drive device209 shown in FIG. 23, but the frequency region indicating inverting ofphase is narrow in the object lens drive device 209 according to thepresent invention. This is because, in the object lens drive device 209shown in FIG. 23, since one end portion 227 of the flexible printedwiring board 226 is attached to the backward surface portion of thebobbin 116, a force which presses toward the supporting shaft 114 fromthe backward direction is rendered from the flexible printed wiringboard 226 with respect to the movable portion 211 so that the movableportion 211 is operated in the state caused to be linearly in contactwith the supporting shaft 114, and sliding loss is therefore large, butin the object lens drive device 209 according to the present invention,since the front end portion of the first junction portion 129 and thefront end portion of the second junction portion 130 of the flexibleprinted wiring board 126 are attached to the lower surface of the baseattachment portion 117 d, a rotational force with the axis extending inthe focusing direction being as center is rendered from the flexibleprinted wiring board 126 with respect to the movable portion 111 so thatthe movable portion 111 is inclined by clearance between the supportinghole 118 and the supporting shaft 114 with respect to the supportingshaft 114, it is moved in the point-contact state, and sliding loss istherefore small.

Accordingly, in the object lens drive device 209 according to thepresent invention, it has been confirmed that the movable portion 111 isoperated in the focusing direction in the state where satisfactorysliding ability is ensured.

FIG. 26 is a graph indicating frequency response, particularly therelationship between amplitude (gain) and frequency when the movableportion 211 or the movable portion 111 is operated in the trackingdirection with respect to the object lens drive device 209 shown in FIG.23 and the object lens drive device 109 according to the presentinvention. J in FIG. 26 is measured value with respect to the objectlens drive device 209 shown in FIG. 23, and K in FIG. 26 is measuredvalue with respect to the object lens drive device 109 according to thepresent invention.

FIG. 27 is a graph indicating frequency response, particularly therelationship between phase and frequency when the movable portion 211 orthe movable portion 111 is operated in the focusing direction withrespect to the object lens drive device 209 shown in FIG. 23 and theobject lens drive device 109 according to the present invention. M inFIG. 27 is measured value with respect to the object lens drive device209 shown in FIG. 23, and N in FIG. 27 is measured value with respect tothe object lens drive device 109 according to the present invention.

As the result of the measurement, in the object lens drive device 209shown in FIG. 23 and the object lens drive device 109 according to thepresent invention, as shown in FIG. 27, the frequency region indicatinginverting of phase is only shifted so that large difference could not beobserved. However, as shown in FIG. 26, there was obtained the resultthat, in the relationship between amplitude and frequency, in the lowerfrequency region, level of gain is low in the object lens drive device209 shown in FIG. 23, but level of gain is high in the object lens drivedevice 109 according to the present invention. This is because, in theobject lens drive device 209 shown in FIG. 23, load by rigidity of theflexible printed wiring board 226 with respect to the movable portion211 is large when the movable portion 211 is operated in the trackingdirection, but, in the object lens drive device 109 according to thepresent invention, load by rigidity of the flexible printed wiring board126 with respect to the movable portion 111 is small when the movableportion 111 is operated in the tracking direction.

In the object lens drive device 109 according to the present invention,it has been confirmed that the movable portion 111 is operated in thetracking direction in the state where load by rigidity of the flexibleprinted wiring board 126 with respect to the movable portion 111 issmall.

Then, explanation will be given in connection with the relationshipbetween the magnetic member 125 for holding the movable portion 111 atthe neutral position in the focusing direction and in the trackingdirection and the flexible printed wiring board 126 (see FIGS. 28 to30).

In FIGS. 28 to 30, for the purpose of conceptually explaining a forcewhich moves movable portion 111 by magnetic member 125 attracted towardmagnets 115, 115 disposed at the fixed portion 110 side to the neutralposition in the focusing direction, a spring 136 is indicated, and forthe purpose of conceptually explaining a force which moves the movableportion 111 to the balance position by elastic force of the flexibleprinted wiring board 126, a spring 137 is indicated. When it is assumedthat force by the magnetic member 125 does not take place, balanceposition of the movable portion 111 is the position where the movableportion 111 is held by balance between self-weight and elastic force ofthe flexible printed wiring board 126.

In the object lens drive device 109, since there exists clearancebetween the supporting hole 118 formed at the movable portion 111 andthe supporting shaft 114, the movable portion 111 is placed in the statewhere it can be inclined in an arbitrary direction by clearance withrespect to the supporting shaft 114. However, when this inclinationdirection is changed during the operation of the movable portion 111,bad influence takes place in the focusing control and the trackingcontrol by the object lens drive device 109. In the object lens drivedevice 109 according to the present invention, it is desirable thatchange does not take place in the inclination direction during theoperation of the movable portion 111 so that the movable portion 111 isoperated in the state inclined in a predetermined direction at all timeswith respect to the supporting shaft 114.

Since a force which moves the movable portion 111 to the neutralposition in the focusing direction by the magnetic member 125 is greaterthan a force rendered to the movable portion 111 by elasticity of theflexible printed wiring board 126, it is necessary to set elastic forceof the flexible printed wiring board 126 so that a force in a directionmoved to the base portion 112 side of the fixed portion 110 is renderedto the movable portion 111 at all times within the movement range in thefocusing direction of the movable portion 111 in order that the movableportion 111 is operated in the state inclined in a predetermineddirection at all times with respect to the supporting shaft 114.Accordingly, it is sufficient that a force in a direction to bias themovable portion 111 toward the base portion 112 side takes place in theflexible printed wiring board 126 at all times. For this reason, in theobject lens drive device 109 of the present invention, the balanceposition is set at the base portion 112 side with respect to themovement end of the base portion 112 side within the movement range inthe focusing direction of the movable portion 111 (see FIG. 31).

For example, in the case where movement range in the focusing directionis upper and lower 0.5 mm (+0.5 mm to −0.5 mm) with the state where themovable portion 111 is held at the neutral position in the focusingdirection (see FIG. 28) being as reference, the balance position is setso that there results the position smaller than −0.5 mm.

By setting the balance position at the base portion 112 side withrespect to the movement end of the base portion 112 side within themovement range in the focusing direction of the movable portion 111 inthis way, in the object lens drive device 109 of the present invention,a force in a direction where its backward end portion is moved to thebase portion 112 side is rendered from the flexible printed wiring board126 to the movable portion 111 at all times so that the movable portion111 is operated in the state inclined in backward lower direction at alltimes, i.e., in the state where the object lens 121 side is inclined insuch a manner that it is positioned at the front end side of thesupporting shaft 114 (see FIGS. 28 to 30). FIG. 28 shows the state wherethe movable portion 111 is held at the neutral position in the focusingdirection, FIG. 29 shows the state where the movable portion 111 ispositioned at the movement end of the upper side in the focusingdirection, and FIG. 30 shows the state where the movable portion 111 ispositioned at the movement end of the lower side in the focusingdirection.

In the object lens drive device 109 according to the present invention,since the movable portion 111 is operated in the state inclined in apredetermined direction at all times with respect to the supportingshaft 114, change does not take place in the inclination directionduring the operation of the movable portion 111 to have ability toensure stable operating state of the movable portion 111 at all times.

Then, a further example of a flexible printed wiring board used in theobject lens drive device according to the present invention will beexplained with reference to FIGS. 32 and 33.

A flexible printed wiring board 156 shown in FIGS. 32 and 33 is adaptedso that the base is formed by material having flexibility, and includesattachment portions 138, 139 attached to fixed portion 110, a derivationportion 140 projected from the attachment portion 138, and first andsecond junction portions 141 and 142.

At the attachment portions 138, 139, there are respectively formed holes138 a, 139 a.

The derivation portion 140 is formed so that it is elongatedsubstantially in a predetermined direction, and is adapted so that fourland portions 140 a for circuit are provided at the front end portion inthe state spaced to each other when viewed in the developed state shownin FIG. 32.

The first junction portion 141 is provided in a manner extended in thesame direction as that of the derivation portion 140 when viewed in thedeveloped state shown in FIG. 32.

When viewed in the developed state shown in FIG. 32, the second junctionportion 142 includes a first portion 142 a projected in a directionperpendicular to the first junction portion 141 and positioned at theattachment portion 138 side, and a second portion 142 b continuous tothe first portion 142 a and extended in the same direction as that ofthe first junction portion 141.

The attachment portion 139 is provided in a manner projected toward theside opposite to the attachment portion 138 in the state where the firstportion 142 a is put therebetween from the end portion of the firstportion 142 a side of the second portion 142 b of the second junctionportion 142.

As shown in FIG. 32, the portion close to the front end of the firstjunction portion 141 and the portion close to the front end of thesecond portion 142 b of the second junction portion 142 are connected bya bridge portion 143. The first junction portion 141 and the secondjunction portion 142 are formed in the state bent perpendicular in sucha manner that the front end portions thereof are respectively close toeach other in the horizontal direction.

At the front end portion of the first junction portion 141, landportions 141 a, 141 a for coil for connecting tracking coil are formed.At the front end portion of the second junction portion 142, landportions 142 c, 142 c for coil for connecting the focusing coil areformed.

At a flexible printed wiring board 156, as shown in FIG. 32, fourcircuit patterns 144, 144, 145, 145 are formed. The circuit patterns144, 144 are circuit patterns to which one coil, e.g., tracking coil 124is connected, and are respectively formed between land portions 140 a,140 a for circuit and land portions 141 a, 141 a for coil. These circuitpatterns extend to the land portions 141 a, 141 a for coil via thederivation portion 140, the attachment portion 138 and the firstjunction portion 141 from the land portions 140 a, 140 a for circuit.The circuit patterns 145, 145 are circuit patterns to which the othercoil, e.g., focusing coil 123 is connected, and are respectively formedbetween the land portions 140 a, 140 a for circuit and the land portions142 c, 142 c for coil. Such circuit patterns extend to the land portions142 c, 142 c for coil via the derivation portion 140, the attachmentportion 138 and the second junction position 142 from the land portions140 a, 140 a for circuit.

The flexible printed wiring board 156 is attached in such a manner thatthe first junction portion 141 and the second junction portion 142connect the fixed portion 110 and the movable portion 111.

The flexible printed wiring board 156 is attached to the lower surfaceof the base portion 112 of the fixed portion 110 in the state where thecentral portion of the first portion 142 a of the second junctionportion 142 is bent so that the first portion 141 a is folded back, andthe attachment portion 138 and the attachment portion 139 overlap witheach other. The supporting shaft 114 is slightly projected toward lowerdirection from the lower surface of the base portion 112, and theattachment portions 138, 139 which have overlapped with each other areattached to the base portion 112 in the state where the lower endportion of the supporting shaft 114 is inserted into holes 138 a, 139 a.The first junction portion 141 and the second junction portion 142 arecurved so as to indicate substantially circular arc shape, and areinserted into slit 117 e for insertion of the movable portion 111 in thestate where the portions close to the front end of the first junctionportion 141 and the second junction portion 142 are in contact with eachother in such a manner that the bridging portion 143 is folded back.Such junction portions are bonded by, e.g., double-faced tape, to thelower surface of the base attachment portion 117 d in the state wherethe portion in which the land portions 141 a, 141 a for coil are formedand the portion in which the land portions 142 c, 142 c for coil areformed are bent in directions opposite to each other.

At this time, the portions close to the front ends of the first junctionportion 141 and the second junction portion 142 of the flexible printedwiring board 156 are inserted into slit 117 e for insertion, and theportion where the land portions 141 a, 141 a for coil are formed and theportion where the land portions 142 c, 142 c for coil are formed areonly bent in directions opposite to each other so that they are bondedto the lower surface of the base attachment portion 117 d. For thisreason, it is possible to extremely easily carry out attachment withrespect to the movable portion 111 of the flexible printed wiring board156.

The flexible printed wiring board 156 shown in FIGS. 32 and 33 can beinserted into slit 117 e for insertion in the state where the bridgingportion 143 which connects the portion close to the front end of thefirst junction portion 141 and the portion close to the second junctionportion 142 is bent back, and the portion close to the front end of thefirst junction portion 141 and the portion close to the front end of thesecond junction portion 142 overlap with each other. For this reason,there is no necessity of separately inserting the first junction portion141 and the second junction portion 142 into the slit 117 e forinsertion. Thus, it is possible to easily carry out attachment withrespect to the base attachment portion 117 d.

In the state where the flexible printed wiring board 156 is attached inthis way, both end portions of the tracking coil 124 are respectivelyconnected to land portions 141 a, 141 a for coil by soldering, and bothend portions of the focusing coil 123 are respectively connected to theland portions 142 c, 142 c for coil by soldering.

In the state where the flexible printed wiring board 156 is attached tothe base attachment portion 117 d, the land portions 141 a, 141 a forcoil to which the tracking coils are connected and the land portions 142c, 142 c for coil to which the focusing coil is connected are bothdirected to the base portion 112 side. For this reason, it is possibleto easily solder both end portions of the tracking coils 124 and bothend portions of the focusing coil 123 with respect to the land portions141 a, 141 a, 142 c, 142 c for coil.

The derivation portion 140 of the flexible printed wiring board 156 isprojected toward the side direction from the fixed portion 110, andplural land portions 140 a for circuit are respectively connected torespective terminal portions of the current supply circuit.

As shown in FIG. 33, the flexible printed wiring board 156 attached in amanner as described above is disposed in such a manner that widthdirection of the first and second junction portions 141 and 142 isperpendicular to the focusing direction, and is perpendicular to thetracking direction. The first junction portion 141 and the secondjunction portion 142 of the flexible printed wiring board 156 aresymmetrically disposed with the plane surface including optical axis 121a of the object lens 121 and central axis 114 a of the supporting shaft114 being as reference.

As stated above, in the object lens drive device 109 according to thepresent invention, even in the case where the flexible printed wiringboard 156 is used, when the movable portion 111 is operated in thefocusing direction and in the tracking direction, load with respect tothe movable portion 111 by rigidity of the flexible printed wiring board156 is small, and improvement of sensitivity of the movable portion 111can be realized. Thus, it is possible to ensure satisfactory operatingstate in the focusing direction and in the tracking direction.

There is no necessity of elongating length of the flexible printedwiring board 156 in order to lessen load with respect to the movableportion 111 by the flexible printed wiring board 156. It is possible torealize miniaturization of the object lens drive device 109 accordingly.

Since the first junction portion 141 and the second junction portion 142of the flexible printed wiring board 156 are symmetrically disposed withthe plane surface including optical axis 121 a of the object lens 121and central axis 114 a of the supporting shaft 114 being as reference,it is possible to stably hold the movable portion 111 it the neutralposition in the tracking direction.

In addition, since circuit patterns 144, 144 in which drive current isdelivered at the time of tracking control and circuit patterns 145, 145in which drive current is delivered at the time of focusing control arerespectively separately formed at the first junction portion 141 and thesecond junction portion 142 of the flexible printed wiring board 156, itis possible to mutually lessen the influence of noise at the firstjunction portion 141 and the second junction portion 142.

Practical forms and structures of respective portions shown in theabove-described embodiments all only show examples in carrying out thepresent invention, and various changes or modifications can be madewithin the scope which does not depart from the gist of the presentinvention.

INDUSTRIAL APPLICABILITY

As described above, in the present invention, by production of theangular moment, the movable portion in which the object lens is attachedis operated in the state inclined in a predetermined direction withrespect to the supporting shaft at all times. As a result, there is nopossibility that change may take place in direction of inclination withrespect to the supporting shaft of the movable portion. Thus, it ispossible to ensure stable operating state of the movable portion. Sincethe movable portion is operated in the state where angular moment in apredetermined direction is produced at all times, it is possible torealize stable focus control and tracking control irrespective of changeof attitude of the movable portion.

Since there is no change in direction of inclination with respect to thesupporting shaft of the movable portion, it is possible to shortenlength of the supporting hole. As a result, it is possible to realizethin structure of the object lens drive device. In addition, sincecenter of line connecting two opening edges of supporting hole of themovable portion and two contact points with respect to the supportingshaft can be positioned on center axis of the supporting shaft portion,balance of the movable portion with respect to the supporting shaft issatisfactory. Thus, it is possible to realize stable focus control andtracking control.

1. An object lens drive device comprising: a fixed portion provided insuch a manner that a supporting shaft is projected; a movable portioncomposed of an object lens, and a bobbin adapted so that the object lensis attached and a hole through which the supporting shaft is inserted isformed, the bobbin being supported in a manner slidably along thesupporting shaft and rotatably with the supporting shaft being ascenter; a coil portion configured to move the movable portion along thesupporting shaft to thereby move the object lens in a focus direction,and to rotate the bobbin with the supporting shaft being as center tothereby move the object lens in a tracking direction; and a flexibleprinted wiring board adapted so that a portion is respectively attachedto the fixed portion and the movable portion to supply power to the coilportion, and the flexible printed wiring board is adapted so that awidth direction of a junction portion which connects the fixed portionand the movable portion is different from the focus direction, and isdifferent from the tracking direction, the flexible printed wiring boardis provided so that width direction of the junction is perpendicular tothe focus direction, and is perpendicular to the tracking direction. 2.The object lens drive device of claim 1, further comprising: supportingmeans for supporting the movable portion in the state inclined withrespect to the supporting shaft, wherein the supporting means comprisesa magnetic member attached to the movable portion and adapted forholding the movable portion at neutral position in the focus directionand in the tracking direction in cooperation with the drive portion. 3.The object lens drive device as set forth in claim 2, wherein thesupporting means comprises a magnetic member attached to the movableportion, and adapted for holding the movable portion at neutral positionin the focus direction and in the tracking direction in cooperation withthe drive portion, the magnetic member being attached to the movableportion in such a manner inclined with respect to the supporting shaft.4. The object lens drive device as set forth in claim 3, wherein themagnetic member is formed to be substantially annular.
 5. The objectlens drive device as set forth in claim 4, wherein the magnetic memberis formed so as to take substantially annular shape in which a portionis cut.
 6. The object lens drive device as set forth in claim 5, whereinthe magnetic member is attached to the bobbin so that inclination anglewith respect to the supporting shaft becomes equal to 20 degrees to 40degrees.
 7. The object lens drive device as set forth in claim 3,wherein the device is adapted so that, in the state where power is notsupplied to the coil portion, position in the focus direction withrespect to the fixed portion of the movable portion by balance betweengravity and elastic force of the flexible printed wiring board is set atthe fixed portion side with respect to movement end of the fixed portionside within movement range in the focus direction of the movableportion.
 8. The object lens drive device as set forth in claim 3,wherein the coil portion comprises a coil body composed of a focus coilattached to the bobbin and plural tracking coils, a yoke portion inwhich the magnet portion is attached being formed at the fixed portion.9. The object lens drive device as set forth in claim 1, furthercomprising: a drive portion including a magnet portion provided ateither one of the fixed portion and the movable portion.
 10. The objectlens drive device as set forth in claim 1, wherein the flexible printedwiring board is adapted so that the junction portion is branched to forma first junction portion and a second junction portion, the firstjunction portion and the second junction portion being symmetricallydisposed with plane surface including optical axis of the object lensand center axis of the supporting shaft being as reference.
 11. A discrecording and/or reproducing apparatus comprising: a rotation drive unitadapted so that disc is loaded to rotationally drive the loaded disc; anoptical pick-up; and a feed mechanism for moving the optical pick-up inradial direction of the disc, wherein the optical pick-up comprises anobject lens drive unit including a fixed portion provided so that asupporting shaft is projected, a movable portion composed of an objectlens and a bobbin adapted so that the object lens is attached and a holethrough which the supporting shaft is inserted is formed, the bobbinbeing supported in a manner movably along the supporting shaft androtatably with the supporting shaft being as center, and a coil portionto move the movable portion along the supporting shaft to thereby movethe object lens in a focus direction, and to rotate the bobbin with thesupporting shaft being as center to thereby move the object lens in atracking direction, and supporting means for supporting the movableportion in the state inclined with respect to the supporting shaft, aflexible printed wiring board adapted so that a portion is respectivelyattached to the fixed portion and the movable portion to supply power tothe coil portion, the flexible printed wiring board is adapted so that awidth direction of a junction portion which connects the fixed portionand the movable portion is different from the focus direction, and isdifferent from the tracking direction, the flexible printed wiring boardis provided so that width direction of the junction portion isperpendicular to the focus direction, and is perpendicular to thetracking direction.
 12. The disc recording and/or reproducing apparatusof claim 11, further comprising: supporting means for supporting themovable portion in the state inclined with respect to the supportingshaft, wherein the supporting means comprises a magnetic member attachedto the movable portion and adapted for holding the movable portion atneutral position in the focus direction and in the tracking direction incooperation with the drive portion.
 13. The disc recording and/orreproducing apparatus as set forth in claim 11, wherein the supportingmeans comprises a magnetic member attached to the movable portion, andadapted for holding the movable portion at neutral position in the focusdirection and in the tracking direction in cooperation with the driveportion, the magnetic member being attached at the movable portion in amanner inclined with respect to the supporting shaft.
 14. The discrecording and/or reproducing apparatus as set forth in claim 13, whereinthe magnetic member is formed to be substantially annular.
 15. The discrecording and/or reproducing apparatus as set forth in claim 14, whereinthe magnetic member is formed so as to take substantially annular shapein which a portion is cut.
 16. The disc recording and/or reproducingapparatus as set forth in claim 15, wherein the magnetic member isattached to the bobbin so that inclination angle with respect to thesupporting shaft becomes equal to 20 degrees to 40 degrees.
 17. The discrecording and/or reproducing apparatus of claim 11, further comprising:a drive portion including a magnet portion provided at either one of thefixed portion and the movable portion.
 18. The disc recording and/orreproducing apparatus as set forth in claim 11, wherein the flexibleprinted wiring board is adapted so that the junction portion is branchedto form a first junction portion and a second junction portion, thefirst junction portion and the second junction portion beingsymmetrically disposed with plane surface including optical axis of theobject lens and center axis of the supporting shaft being as center. 19.The disc recording and/or reproducing apparatus as set forth in claim11, wherein the object lens drive unit is adapted so that, in the statewhere power is not supplied to the coil portion, position in the focusdirection with respect to the fixed portion of the movable portion bybalance between gravity and elastic force of the flexible printed wiringboard is set at the fixed portion side with respect to movement end ofthe fixed portion side within movement range in the focus direction ofthe movable portion.
 20. The disc recording and/or reproducing apparatusas set forth in claim 11, wherein the coil portion comprises a coil bodycomposed of a focus coil attached to the bobbin, and plural trackingcoils, a yoke portion to which the magnetic portion is attached beingformed at the fixed portion.